Arsenal staged a stunning League Cup fightback at Reading after trailing 4-0 in the first half on Tuesday,advancing to the quarterfinals with a 7-5 extra-time victory after Theo Walcott scored a hat trick,including strikes in injury time in both halves,and then in the last minute of extra time. The game that was branded the greatest ever Cup comeback. It was an unbelievable game. Im absolutely knackered now, Walcott said. Weve scored seven goals away from home - it was great going forward. Maybe defensively it wasnt great at times,but were in the draw and thats what matters. Arsenals performance in the first half was so poor that some Gunners fans left the stadium after the team conceded a fourth goal in the 37th minute as Reading dominated against its Premier League rival. But after Walcott pulled one back just before halftime,he took the game into extra time with a last-gasp equalizer in the sixth minute of stoppage time. Substitute Olivier Giroud had netted the second for Arsenal and Laurent Koscielny,who earlier scored an own goal,made it 4-3 in the 89th. Marouane Chamakh put Arsenal ahead for the first time in extra time with his first goal in almost a year,but Reading drew level again when Pavel Pogrebnyak made it 5-5 with four minutes to go. Walcott then completed his hat trick by slotting in a rebound from Andrei Arshavins effort,and Chamakh lobbed goalkeeper Adam Federici in the closing exchanges to ensure Arsenal advanced. You always see new things in our game,thats why its never boring, Arsenal manager Arsene Wenger said. It was a tennis match today. They had a fantastic start,we were not sharp and it was 4-0 and could have been one or two more. . You cannot play for Arsenal and give up. Reading manager Brian McDermott was aggrieved that Walcotts goal that took the game into extra time came more than five minutes into stoppage time when only four had been signaled by the fourth official. If its four minutes,you dont mind another 30 seconds but not another two minutes, McDermott said. I was waiting for him to blow his whistle but hell have his reasons. . What happened tonight was extraordinary. On a thrilling night for English footballs second-tier knockout competition,three Premier League clubs - Southampton,Sunderland and Wigan - were beaten by lower-league opposition. The biggest shock came at Wigan where fourth-tier club Bradford won a penalty shootout 4-2 after the match ended 0-0. Premier League struggler Southampton exited after losing 3-0 to Leeds of the League Championship. Goals from Michael Tonge and El-Hadji Diouf as well as Luciano Becchios penalty kick steered Leeds into the quarterfinals for the first time since 1996. We didnt perform anywhere near whats expected of a Southampton Football Club team, said Southampton manager Nigel Adkins,who made 11 changes from the side that lost to Tottenham on Sunday. Middlesbrough advanced after Scott McDonalds goal secured a 1-0 victory at northeast rival Sunderland. It was a nervy night for Aston Villa,which only eliminated third-tier club Swindon 3-2 after Christian Bentekes 90th minute goal. Villa appeared to be cruising to victory after goals from Benteke and Gabriel Agbonlahor before halftime. But Swindon subsitute Miles Storey scored twice after the break to make it 2-2 before Benteke turned in a cross from Eric Lichaj.